Sliding structure location on a pointing device corrected for non-linearity of measured differential

Abstract

A pointing device has a pointing device surface and a sliding structure that moves with respect to the pointing device surface. A detector outputs a value that varies as the sliding structure moves with respect to the pointing device surface. A controller estimates the sliding structure location on the pointing device surface by calculating an approximate distance. The approximate distance is calculated by multiplying a measured differential of the value times a conversion constant. The controller adjusts the approximate distance to take into account non-linearity of the measured differential.

1 . A method for calculating a sliding structure location on a pointing device surface, the method comprising: 
 calculating an approximate distance by multiplying a measured differential times a conversion constant; and,    adjusting the approximate distance to take into account non-linearity of the measured differential.    
     
     
         2 . A method as in  claim 1  wherein the measured differential is a measured capacitance differential.  
     
     
         3 . A method as in  claim 1  wherein the measured differential is one of the following: 
 a magnetic field differential;    a resistance differential; or,    an inductance differential.    
     
     
         4 . A method as in  claim 1  wherein adjusting the approximate distance is performed using a first order correction value.  
     
     
         5 . A method as in  claim 1  wherein adjusting the approximate distance is performed using one or more tables.  
     
     
         6 . A method as in  claim 1  wherein adjusting the approximate distance in an “x” direction is performed using the following equation: 
 If |A|<=Start, then 
 Delta X=A  
   If |A|>Start, then 
 If A>0, then 
 Delta X=A+(A−Start)*Slope  
 
 If A<0, then 
 Delta X=A+(A+Start)*Slope  
 
   wherein A is the approximate distance in the x direction, Delta X is an adjusted value in the x direction, “Start” is a threshold value and “Slope” is a first order correctional value constant.    
     
     
         7 . A method as in  claim 6  wherein adjusting the approximate distance in a “y” direction is performed using the following equation: 
 If |B|<=Start, then 
 Delta X=B  
   If |B|>Start, then 
 If B>0, then 
 Delta X=B+(B−Start)*Slope  
 
 If B<0, then 
 Delta X=B+(B+Start)*Slope  
 
   wherein B is the approximate distance and Delta Y is an adjusted value in the Y direction.    
     
     
         8 . A pointing device, comprising: 
 a pointing device surface;    a sliding structure that moves with respect to the pointing device surface;    a detector that outputs a value that varies as the sliding structure that moves with respect to the pointing device surface; and    a controller that estimates the sliding structure location on the pointing device surface by calculating an approximate distance, the approximate distance being calculated by multiplying a measured differential of the value times a conversion constant, the controller adjusting the approximate distance to take into account non-linearity of the measured differential.    
     
     
         9 . A pointing device as in  claim 8  wherein the measured differential is a measured capacitance differential.  
     
     
         10 . A pointing device as in  claim 8  wherein the measured differential is one of the following: 
 a magnetic field differential;    a resistance differential; or, an inductance differential.    
     
     
         11 . A pointing device as in  claim 8  wherein adjusting the approximate distance is performed using a first order correction value.  
     
     
         12 . A pointing device as in  claim 8  wherein adjusting the approximate distance is performed using one or more tables.  
     
     
         13 . A pointing device as in  claim 8  wherein adjusting the approximate distance in an “x” direction is performed using the following equation: 
 If |A|<=Start, then 
 Delta X=A  
   If |A|>Start, then 
 If A>0, then 
 Delta X=A+(A−Start)*Slope  
 
 If A<0, then 
 Delta X=A+(A+Start)*Slope  
 
   wherein A is the approximate distance in the x direction, Delta X is an adjusted value in the x direction, “Start” is a threshold value and “Slope” is a first order correctional value constant.    
     
     
         14 . A pointing device as in  claim 13  wherein adjusting the approximate distance in a “y” direction is performed using the following equation: 
 If |B|<=Start, then 
 Delta X=B  
   If |B|>Start, then 
 If B>0, then 
 Delta X=B+(B−Start)*Slope  
 
 If B<0, then 
 Delta X=B+(B+Start)*Slope  
 
   wherein B is the approximate distance and Delta Y is an adjusted value in the Y direction.    
     
     
         15 . A computing device, comprising: 
 a pointing device, the pointing device including: 
 a pointing device surface;  
 a sliding structure that moves with respect to the pointing device surface;  
 means for generating a value that varies as the sliding structure moves with respect to the pointing device surface; and  
 means for calculating the sliding structure location on the pointing device surface by calculating an approximate distance, the approximate distance being calculated by multiplying a measured differential of the value times a conversion constant; wherein the approximate distance is adjusted to take into account non-linearity of the measured differential.  
   
     
     
         16 . A computing device as in  claim 15  wherein the measured differential is a measured capacitance differential.  
     
     
         17 . A computing device as in  claim 15  wherein adjusting the approximate distance is performed using a first order correction value.  
     
     
         18 . A computing device as in  claim 15  wherein adjusting the approximate distance is performed using one or more tables.  
     
     
         19 . A computing device as in  claim 15  wherein adjusting the approximate distance in an “x” direction is performed using the following equation: 
 If |A|<=Start, then 
 Delta X=A  
   If |A|>Start, then 
 If A>0, then 
 Delta X=A+(A−Start)*Slope  
 
 If A<0, then 
 Delta X=A+(A+Start)*Slope  
 
   wherein A is the approximate distance in the x direction, Delta X is an adjusted value in the x direction, “Start” is a threshold value and “Slope” is a first order correctional value constant.    
     
     
         20 . A computing device as in  claim 15  wherein adjusting the approximate distance in a “y” direction is performed using the following equation: 
 If |B|<=Start, then 
 Delta X=B  
   If |B|>Start, then 
 If B>0, then 
 Delta X=B+(B−Start)*Slope  
 
 If B<0, then 
 Delta X=B+(B+Start)*Slope  
 
   wherein B is the approximate distance and Delta Y is an adjusted value in the Y direction.